The effect of ouabain and ethacrynic acid on ATPase activities in the inner ear of the rat and guinea pig.

The effect of ethacrynic acid on ATPase activities in the stria vascularis of rat and guinea pig inner ear was studied. Both Na-K- and Mg-activated ATPase activities were inhibited non-selectively only at very high concentrations of ethacrynic acid, in contrast to the selective inhibition of Na-K-ATPase activity by ouabain. It is suggested that the deleterious effect of ethacrynic acid on the inner ear may be due to its effect on the general metabolism of the cell rather than on the ionic transport system.